Hill Ranges of the Peninsular Plateau

Most of the hills in the peninsular region are of the relict type (residual hills).

They are the remnants of the hills and horsts formed many million years ago (horst: uplifted block; graben: subsided block).

The plateaus of the Peninsular region are separated from one another by these hill ranges and various river valleys.

Aravali Range

They are aligned in north-east to south-west direction.

They run for about 800 km between Delhi and Palanpur in Gujarat.

They are one of the oldest (very old) fold mountains of the world and the oldest in India. {Fold Mountains – Block Mountains}

After its formation in Archaean Era (several 100 million years ago), its summits were nourishing glaciers and several summits were probably higher than the present day Himalayas.

Now they are relict (remnants after severe weathering and erosion since millions of years) of the world’s oldest mountain formed as a result of folding (Archaean Era).

They continue up to Hariddwar buried under the alluvium of Ganga Plains.

The range is conspicuous in Rajasthan (continuous range south of Ajmer where it rises to 900 m.) but becomes less distinct in Haryana and Delhi (characterized by a chain of detached and discontinuous ridges beyond Ajmer).

According to some geographers, one Branch of the Aravalis extends to the Lakshadweep Archipelago through the Gulf of Khambhat and the other into Andhra Pradesh and Karnataka.

It’s general elevation is only 400-600 m, with few hills well above 1,000 m.

At the south-west extremity the range rises to over 1,000 m. Here Mt. Abu (1,158 m), a small hilly block, is separated from the main range by the valley of the Banas. Guru Sikhar (1,722 m), the highest peak, is situated in Mt. Abu.

Vindhyan Range

The Vindhyan Range, overlooking (have a view of from above) the Narmada valley, rises as an escarpment (a long, steep slope at the edge of a plateau or separating areas of land at different heights) flanking (neighboring on one side) the northern edge of the Narmada-Son Trough (the rift through which the Narmada river flows)(trough is opposite of ridge. It is a narrow depression).

It runs more or less parallel to the Narmada Valley in an east-west direction from Jobat in Gujarat to Sasaram in Bihar for a distance of over 1,200 km.

The general elevation of the Vindhyan Range is 300 to 650 m.

Most parts of the Vindhayan Range are composed of horizontally bedded sedimentary rocks of ancient age. {Rock System}

The Vindhyas are continued eastwards as the Bharner and Kaimur hills.

This range acts as a watershed between the Ganga system and the river systems of south India.

The rivers Chambal, Betwa and Ken rise within 30 km of the Narmada.

Satpura Range

Satpura range is a series of seven mountains (‘Sat’ = seven and ‘pura’ = mountains)

It runs in an east-west direction south of the Vindhyas and in between the Narmada and the Tapi, roughly parallel to these rivers.

It stretches for a distance of about 900 km.

Parts of the Satpuras have been folded and upheaved. They are regarded as structural uplift or ‘horst’.

Dhupgarh (1,350 m) near Pachmarhi on Mahadev Hills is the highest peak.

Amarkantak (1,127 m) is another important peak.

Western Ghats (or The Sahyadris)

They form the western edge of the Deccan tableland.

Run from the Tapi valley (21° N latitude) to a little north of Kanniyakumari (11° N latitude) for a distance of 1,600 km.

Thal ghat and Bhor ghat are important passes which provide passage by road and rail between the Konkan Plains in the west and the Deccan Plateau in the east.

[Konkan coast == Maharashtra coast and Goa coast;

Malabar Coast == Kerala and Karnataka coast]

The Middle Sahyadri

The Middle Sahyadri runs from 16°N latitude upto Nilgiri hills.

This part is made of granites and gneisses.

This area is covered with dense forests.

The western scarp is considerably dissected by headward erosion of the west flowing streams.

The average height is 1200 m but many peaks exceed 1500 m.

The Vavul Mala (2,339 m), the Kudremukh (1,892 m) and Pashpagiri (1,714 m) are important peaks.

The Nilgiri Hills which join the Sahyadris near the trijunction of Karnataka, Kerala and TN, rise abruptly to over 2,000 m.

They mark the junction of the Western Ghats with Eastern Ghats.

Doda Betta (2,637 m) and Makurti (2,554 m) are important peaks of this area.

The southern section

The southern part of the Western Ghats is separated from the main Sahyadri range by Pal ghat Gap [Palakkad Gap].

The high ranges terminate abruptly on either side of this gap.

Pal ghat Gap it is a rift valley. This gap is used by a number of roads and railway lines to connect the plains of Tamil Nadu with the coastal plain of Kerala.

It is through this gap that moist-bearing clouds of the south-west monsoon can penetrate some distance inland, bringing rain to Mysore region.

South of the Pal ghat Gap there is an intricate system of steep and rugged slopes on both the eastern and western sides of the Ghats.

Anai Mudi (2,695 m) is the highest peak in the whole of southern India.

Three ranges radiate in different directions from Anai Mudi. These ranges are the Anaimalai (1800-2000 m) to the north, the Palani (900-1,200 m) to the north-east and the Cardamom Hills or the Ealaimalai to the south.

Eastern Ghats

Eastern Ghats run almost parallel to the east coast of India leaving broad plains between their base and the coast.

It is a chain of highly broken and detached hills starting from the Mahanadi in Odisha to the Vagai in Tamil Nadu. They almost disappear between the Godavari and the Krishna.

Between the Godavari and the Krishna rivers, the Eastern Ghats lose their hilly character and are occupied by Gondwana formations (KG Basin is here).

The Eastern Ghats reappear as more or less a continuous hill range in Cuddapah and Kurnool districts of Andhra Pradesh where they are called as Nallamalai Range [Naxalite hideout in AP] with general elevation of 600-850 m.

The southern part of this range is called the Palkodna range.

To the south, the hills and plateaus attain very low altitudes; only Javadi Hills and the Shevroy-Kalrayan Hills form two distinct features of 1,000 m elevation.

The Biligiri Rangan Hills in Karnataka (at its border with Tamil Nadu) attain a height of 1,279 m.